Ceramic electronic component, substrate arrangement, and method of manufacturing ceramic electronic component

Abstract

A ceramic electronic component includes an element body having a dielectric and internal electrodes, the element body having an upper surface, a lower surface, and side surfaces; external electrodes formed on multiple surfaces of the element body, and an oxide layer formed on the upper surface of the element body. Each of the external electrodes has a base layer and a plating layer, the base layer containing metal and having a lower part formed on the lower surface of the element body and a side part formed on one of the side surfaces of the element body and being connected to one or more of the internal electrodes, the plating layers being formed on the lower part of the corresponding base layer. The oxide layer has a surface roughness Ra that is equal to or greater than 0.20 micrometers.

What is claimed is: 
     
       1. A ceramic electronic component comprising:
 an element body including a dielectric and internal electrodes, the element body having an upper surface, a lower surface, and side surfaces; 
 external electrodes formed on multiple surfaces of the element body, each of the external electrodes including a base layer and a plating layer, the base layer containing metal and having a lower part formed on the lower surface of the element body and a side part formed on one of the side surfaces of the element body and being connected to one or more of the internal electrodes, the plating layer being formed on the lower part of the corresponding base layer; and 
 an oxide layer formed on the upper surface of the element body, the oxide layer having a surface roughness Ra that is equal to or greater than 0.20 micrometers. 
 
     
     
       2. The ceramic electronic component according to  claim 1 ,
 wherein the base layer of each of the external electrodes further includes an upper part formed on the upper surface of the element body, and 
 wherein the oxide layer is formed on the upper parts of the base layers. 
 
     
     
       3. The ceramic electronic component according to  claim 1 , wherein the base layers of each of the external electrodes further includes an upper part formed on the upper surface of the element body,
 wherein the oxide layer continuously covers the upper surface of the element body and the respective upper parts and the side parts of the base layers of the external electrodes, and 
 wherein the plating layer of each of the external electrodes is formed on the lower part and the side part of the corresponding base layer and is in contact with the oxide layer on the side part of the base layer, the plating layers of each of the external electrodes being absent on the upper surface of the element body. 
 
     
     
       4. The ceramic electronic component according to  claim 1 , wherein the element body further has a front surface and a rear surface,
 wherein the base layer of each of the external electrodes further includes an upper part formed on the upper surface of the element body, a front part formed on the front surface of the element body, and a rear part formed on the rear surface of the element body, 
 wherein the oxide layer continuously covers the upper surface, the front surface, and the rear surface of the element body, and the upper parts, the side parts, the front parts, and the rear parts of the base layers of the external electrodes, and 
 wherein the plating layer of each of the external electrodes is formed on the lower part, the side part, the front part, and the rear part of the corresponding base layer and is in contact with the oxide layer on the side part, the front part, and the rear part of the base layer, the plating layer of each of the external electrodes being absent on the upper surface of the element body. 
 
     
     
       5. The ceramic electronic component according to  claim 1 , wherein the oxide layer further includes side parts formed on the respective side parts of the base layers, and
 wherein the plating layer of each of the external electrodes is absent on an upper surface of the oxide layer, and covers one of the side parts of the oxide layer. 
 
     
     
       6. The ceramic electronic component according to  claim 1 , wherein the oxide layer further includes side parts formed on the respective side parts of the base layers, and
 wherein each of the side parts of the oxide layer has a lower edge located in a range having an upper limit and a lower limit, the upper limit being distant at least 10 micrometers from an upper surface of the oxide layer, the lower limit being from the upper surface of the oxide layer within a half of a distance between the upper surface of the oxide layer and a lower surface of the external electrode. 
 
     
     
       7. The ceramic electronic component according to  claim 1 , wherein a distance between an upper surface of the oxide layer and a lower surface of the external electrode is 150 micrometers or less. 
     
     
       8. The ceramic electronic component according to  claim 1 , wherein the oxide layer has a thickness that is from one micrometer to five micrometers. 
     
     
       9. The ceramic electronic component according to  claim 1 , wherein the dielectric is made of a material having a main component, and wherein the oxide layer is made of a material having a main component that is the same as the main component of the dielectric. 
     
     
       10. The ceramic electronic component according to  claim 1 , wherein the oxide layer is made of an oxide ceramic. 
     
     
       11. The ceramic electronic component according to  claim 1 , wherein the oxide layer is made of a material containing at least one of barium titanate, strontium titanate, calcium titanate, magnesium titanate, barium strontium titanate, barium calcium titanate, calcium zirconate, barium zirconate, calcium titanate zirconate, titanium oxide, silicon oxide, and aluminum oxide. 
     
     
       12. The ceramic electronic component according to  claim 1 , wherein the base layer of each of the external electrodes contains a co-material dispersed in the metal. 
     
     
       13. The ceramic electronic component according to  claim 12 , wherein the co-material is an oxide ceramic. 
     
     
       14. The ceramic electronic component according to  claim 1 , wherein the element body is a laminate in which first internal electrode layers and second internal electrode layers are alternately stacked with dielectric layers interposed therebetween,
 wherein the external electrodes include a first external electrode and a second external electrode provided on mutually opposing sides of the laminate, 
 wherein the first internal electrode layers are connected to the first external electrode, and 
 wherein the second internal electrode layers are connected to the second external electrode. 
 
     
     
       15. The ceramic electronic component according to  claim 1 , wherein the surface roughness of the oxide layer is greater than a surface roughness of the element body and a surface roughness of the base layer. 
     
     
       16. An arrangement comprising:
 a mounting substrate; and 
 the ceramic electronic component according to  claim 1  mounted on a surface of the mounting substrate, the ceramic electronic component being connected to the mounting substrate via solder layers, the solder layers being adhered to the plating layers of the external electrodes, respectively, 
 wherein each of the solder layers is in surface contact with a side surface of the corresponding plating layer and is located below an upper surface of the oxide layer. 
 
     
     
       17. The arrangement according to  claim 16 , further comprising a resin layer that encapsulates the ceramic electronic component on the mounting substrate, no gap existing between the resin layer and the oxide layer through which moisture can ingress. 
     
     
       18. The arrangement according to  claim 17 , further comprising solder balls formed on the surface of the mounting substrate, the surface being the same as the surface on which the ceramic electronic component is mounted. 
     
     
       19. The arrangement according to  claim 18 , further comprising another mounting substrate connected electrically with the mounting substrate via the solder balls, wherein the ceramic electronic component is interposed between the mounting substrate and said another mounting substrate. 
     
     
       20. A method of manufacturing a ceramic electronic component, the method comprising:
 forming an element body that includes a dielectric and internal electrodes, the element body having an upper surface, a lower surface, and side surfaces; 
 applying a base material for base layers of external electrodes onto the lower surface and the side surfaces of the element body; 
 applying an oxide material for an oxide layer onto the upper surface of the element body and onto portions of the base material that are on the side surfaces; 
 thereafter, sintering the base material and the oxide material to form the base layers of the external electrodes and the oxide layer, the base layer of each of the external electrodes having a lower part formed on the lower surface of the element body and a side part formed on one of the side surfaces of the element body and being connected to one or more of the internal electrodes, the oxide layer being formed on the upper surface of the element body and on the respective portions of the base layers on the side surfaces, the oxide layer having a surface roughness Ra that is equal to or greater than 0.20 micrometers; and 
 forming plating layers on the base layers, respectively, each of the plating layers being formed on the lower part and the side part of one of the base layers.